Signaling system



Dm., 3, 1935. Hl L. HARRIS Er AL SIGNALING SYSTEM Filed Oct. 7, 1953 2 Sheets-Sheet l mi.. Hwll Inusn Drs Haz-'us5 LHarrzs Elernsrd'Dl-:zllzs NNI INN E 3 w35 H. L. HARRIS Er Al.

SIGNALIN'G SYSTEM Filed Oct. '7, 1935 2 Sheets-Sheet 2 l'zuEz-z nrs- Harvey LHarrls Barnard' D.1n[1ll1s HIT-:2,

Patented Dec. 3, 1935 UNITED STATES SIGNALING SYSTEM Harvey L. Harris, Chicago, and Bernard D. Willis, Dak Park, lill., assignors to Associated Electric Laboratories, Inc., Chicago, Ill., a corporation of Delaware Application October 7, 1933, Serial No. 692,572

14 Claims.

This invention relates in general to signaling systems, but more particularly to a signal system designed for use in regulating the movement of vehicles such as taxi-cabs, and the principal Object of the invention resides in the provision of a signaling system that is simple to operate, requires a minimum amount of equipment and is at all times reliable and accurate in the performance of its intended functions.

In metropolitan centers considerable diculty is experienced in properly regulating the movement of motor Vehicles through the crowded streets, resulting in blockades or trafc jams and the consequent slow movement of the vehicles, thereby causing enormous losses of time and money as is Well known. A factor contributing largely to the congestion of traic resides in the almost continuous cruising or idle movement of public taxi-cabs on the lookout for passengers. Accordingly, it is an object of this invention to entirely eliminate this unnecessary movement of taxi-cabs and still render them available to patrons at practically an instants notice.

A further object of the invention is to govern the movement of taxi-cabs in such manner that they Will always be under complete control of a centrally located supervision point or cabstand.

A feature of the invention is concerned with the means whereby a patron in summoning a cab over the signaling system has his call button automatically locked up until the call is actually answered at the cab-stand by the dispatch of a cab to his service of which the patron will be immediately informed by the release of the call button.

A further feature resides in the means whereby each call for taxi-cab service is automatically registered at a main supervisors position over a telephone circuit extending to the cab-stand and over which circuit a diierentiation is automatically made between regular telephone calls and registration calls.

Other features and objects not particularly pointed out will be readily apparent from the description of the invention which together with the two sheets of drawings diagrammatically depict by means of the usual circuit schematic, the principles involved.

Referring to the drawings, Fig. l illustrates the broad general arrangement of the relationship between the call stations', control stations, and supervisors position; Fig. 2 shows the circuit arrangement of a preferred embodiment of the invention with sunicent apparatus to enable a PATENT OFFICE clear understanding of the same; while Fig. 3 illustrates a modiiication in which slightly more apparatus is involved to give a different control over the calls.

Referring now more particularly to Fig. 1 the general arrangement and rel ticnship of thcvarious parts of the system will be described. It will be assumed that the equipment is to be installed in a city or town which is of such a size that a ,i f central or supervisory position can be provided 10 together with a number of distantly located radiating cab-stands or control stations. Each cab-stand is connected with the supervisors position over a single pair of conductors. Radiating from each of the cab-stands may be any numl5 ber of single conductor lines each of which may contain any number of call stations. These call stations may be arranged on a line so that they are located short distances from one another, for example, three or four call stations within a 20 city block, or any desired number of these call stations may be mounted immediately adjacent one another at a single position. Each of the call stations consists of a calling push button together with a releasing magnet. This equipment may be 25 mounted in a suitable box inside the entrances of hotels, stores, oice buildings, etc., where it will be under the casual observation of the door-man, cigar counter clerks, or other attendants, so that malicious operation of the push buttons by unauthorized persons will be prevented.

At the cab-stand or control station to which the single conductor line extending to the call boxes is connected, suitable equipment is provided whereby a permanent registration of the number of calls received over the particular line is made, together with a signal to indicate each time a call is made. Means are likewise provided at the cab-stand for releasing a locked-up call and also for establishing telephonie communication with a supervisors position. All of the cab drivers together with their taxi-cabs are concentrated at the cab-stand when they are idle. The supervisors position is provided with means for calling any of the cab-stands. Each of the other lines extending to the cab-stand is provided with equipment similar to that pointed out. A common general signal is flashed at the cab-stand in response to a call from any station on any one of the lines, while an individual signal is actuated to indicate the particular line from which the call is made.

A detailed explanation of the operation of the system in connection with Fig. 2 will now be pointed out. It will be assumed that a patron 55 "L tains.

desiring taxi-cab service has approached the immediate vicinity in which the call station A is located. This call station A may be the only station at this particular location, or there may be a number of other call stations, B and C, mounted immediately adjacent to call station A, or call buttons A, B, C, etc., may be mounted in one call box. In the former case, stations B and C would be located somewhere in the immediate vicinity. For service the patron merely presses down the push button 8 which is advantageously positioned within reach, and thereby moves a relatively stiff spring 9 into engagement with contact spring II and opens contact spring I from contact spring II. As a further result of the pressing of push button 8 the end of the spring 9 is locked behind a latch I which is under control of the release magnet 5. As a result of this action a circuit is closed extending from ground through the winding of release magnet 5, contact springs 9 and II, line conductor 2, to line equipment LC at the cab-stand, winding of relay I5, winding of meter relay 29, to battery. The resistance of the winding of meter magnet 20, and that of release magnet 5, is of'sucllow value that they cannot energize a sufficient amount to operate their armatures due to the relatively high resistance of relay I5, and the large number of turns it con- Relay I5, however, does energize and at its front contact and armature I places ground through lamp L, common-conductor 28, through the winding of relay 25 to battery. The lamp L, relay I5, meter 20, and the acknowledging key I8 which constitutes the line equipment LC is individual to the line 2, and similar equipment LC-I is provided for the line 2 extending to other dall stations, the remaining equipment at the cab-stand being common to all of the lines. This may all be mounted in a suitable cabinet at the cab-stand in any convenient manner desired. As a result of the operation of relay I5 the lamp L is illuminated indicating at the cab-stand that a call has been made from a station on line 2. Relay 25 upon operating closes its grounded front contact on its armature 26 to establish a circuit through the flashing lamp FL and the constantly rotating circuit interrupter 21 to battery. As a result, lamp FL is rapidly flashed on and off to call the attention of the group of taxi-cab drivers at the cab-station to the illumination of lamp L.

The rst in line of waiting drivers will note down the location of the c-all and acce-pts the summons by momentarily pressing the associated acknowledgment key or button I8, which closes the contact springs I9 and thereby short circuits high resistance relay I5. yRelay I5, upon deenergizing, opens its armature I6 to extinguish the line lamp L and the circuit through relay 25 to stop the ashing of lamp FL. A further result of the operation of key I8 results in the closing of a circuit extending from battery through the winding of meter relay 29, contacts I9 of the acknowledging key I8, line conductor 2, contact springs II and 9 of calling key 8, through the winding of low resistance release magnet 5 to ground. The high resistance relay I5 being no longer in circuit, release relay 5 and meter relay energize in series. As a result of the energization of release magnet 5 it attracts its armature spring 6 to its front contact so that it is held operated or locked up as long as the key I8 is pressed down, although in actual practice this will be only momentarily. At the back contact of armature E the line 3 extending to the station B is temporarily opened to prevent the extension of further calls at this time. Release magnet 5 upon operating latching armature 'I disengages the latch from the spring 9 to permit the push button 8 to restore to its normal position under the tension of spring 9. With key I8 released magnet 5 restores to normal. Station A is now ready to be operated again for another call.

Returning now to the operation of meter relay 2G, in addition to operating its meter to register the call on the line,rit closes ground on its front contact and armature 2I over common conductor 29 through one coil of the ringer magnets R, line conductor 33 extending to the supervlsors position, lower winding of differential relay S0 and lower winding of relay 35 to battery. The differential relay 39 having its windings unbalanced operates and closes the front contact of armature 32 through the winding of meter magnet 38 to battery. The meter magnet 38 actuates its armature to operate the meter and register the fact at the supervisors position that a call has been answered at the cab-stand. The meter relay 20 indicates the particular line from which the call was made, while meter 38 indicates the total calls answered at the cab-stand. Differential relay 39 in energizing likewise disengages its armature SI from its grounded back contact to prevent the closing of this ground through armature 36 and the front contact of relay 35 which relay likewise venergizes at this time but without eiect. As soon as meter relay 20 falls back due to the release of key I8 it opens grounded armature 2i and permits relays 39 and 35 to restore to normal.

It will be assumed that during the time that the push button 8 at the call station A is operated other calls are made from stations B and C by the operation of their respective push buttons. In this event the preceding stations automatically cut 01T the other stations on the line by the opening of their Contact springs IB. The push buttons, however, remain mechanically latched down. When the calls are acknowledged by the operation oi the acknowledging key I8 the iirst station on the line which has made a call is automatically released and the next station in the series extends a call over the extension lines 3 or 4, through the back contact and armature 5 of the release magnet 5, contact springs I9 and II, to the line 2. The acknowledging oi this call at station B will likewise release its push button so that the call from station C can be received over extension line d. From the foregoing it is seen that any number of stations may be operated one at a time or simultaneously and each will be received in succession as the preceding one is released at the cab-stand. The patron desiring the taxi-cab is informed that his call is received at the cab-stand by noting the restoration of the push button 8 which indicates that cab has been immediately dispatched to his service. The line conductor 2, it will be seen, extends in series circuit through the extension lines 3 and 4, between all of the call stations and may terminate in conductor I2 as an open conductor.

In certain instances it may be desirable for a cab driver to communicate with a supervisors position for particular orders. In order to do this the telephone TL is provided at the cabstand. The removal of the receiver closes the usual loop circuit extending through the primary of the induction coil over line conductors 33 and 34 extending to the supervisors position, through upper and lower windings of differential relay 38, to battery and ground through the upper and lower windings of relay 35. Both windings of the differential relay 3!) being now in opposition this relay cannot energize to attract its armature. Relay 35, however, energizes and closes front contact on its armature 36 completing a circuit from grounded back contact of armature 3l, normally closed contact springs 31 of talking key TK, through the lamp AL to battery. The illuminating of the lamp AL informs the supervisor that a call over the lines 33 and 34 is waiting to be answered. In answering the supervisor operates the key TK thereby opening thecontacts 31 to extinguish the call lamp AL, and at the other contact springs of this key close the Acircuit through to the common handset HS. Conversation between the cab-stand telephone IL and the supervisors telephone may now proceed, battery being furnished for each telephone through the windings of relay 35. When the respective telephones are restored to their normal position and the talking key TK is released the equipment assumes its normal position.

In case the supervisor at the supervisory position desires to communicate with the cab-stand he operates the non-locking ringing key RK, thereby closing the contacts of this key and projecting ringing current from the common alternating current generator over the line conductors 33 and 34 through the ringer coils R and the condenser. The ringer operates and attracts the attention of a driver at the cab-stand who thereupon removes the receiver from the tele- 'phone TL to answer the call. This action operates the relay 35 to close its front contact at armature 35 and illuminate lamp AL to indicate to the supervisor that the call has been answered and he thereupon throws his telephone key TK to talking position and converses with the party at the cab-stand.

Referring now particularly to Fig. 3, this drawing illustrates a modied form of the arrangement shown in Fig. 2. The modification consists principally in the provision of a call finding switch at the cab-stand, and means whereby the incoming calls are locked up under direct control of the supervisors position instead of the cab-stand. The general arrangement of the systern, however, as well as the circuit arrangement and equipment at each of the call stations, will be similar to that of Fig. 2.

In describing a call in this system it will be assumed that the calling button 8 at the call station A is operated and lccked under control of the release magnet 5 in a manner similar to that described in Fig. 2. Ground is closed through the winding of low resistance release magnet 5, contact springs 9 and li, line conductor 2, through the winding ofV relatively high resistance relay 4D to battery. This relay is likewise arranged to be slow to operate due to a copper slug Y on its armature end. Release magnet 5 does not operate over this circuit, but relay 40 does. At front contact of armature il ground is extended to bank contact 64 accessible to wiper 61 for a purpose which will be hereinafter pointed out. At grounded iront contact of armature 42 a circuit is closed extending over common start conductor 63, to armature and its back contact, bank contact and armature 82, through the winding of slow to release relay 85 to battery, to start the operation of the call finder switch CF. This switch is of well known construction in which a number of wipers 61, 68 and 69 are driven in a forward direction over a series of bank contacts under control of a stepping magnet 98 and in which the wipers remain in the position in which they were last. used. Relay 85 operates and as a result closes its front contacts on armature 86 to complete a circuit extending from grounded back contact and armature 16, armature 8| and its back contact through the winding of stepping magnet 90 of switch CF to battery. The stepping magnet S0 by means of its pawl and a ratchet advances the wipers 51, 68 and 69 one step onto the next set of bank contacts. At its grounded front contact and armature 9! it likewise extends ground through the lower winding of relay 15 to battery. Relay 15 upon energizing opens its grounded back contact from armature 16 to deenergize the stepping magnet 98. Stepping magnet 90 in turn opens grounded front contact and armature 9| to open the circuit of relay 15. This interaction between stepping magnet 90 and relay 15 continues while at the same time the wipers 61, 68 and 59 are driven step by stepin a forward direction over the bank contacts.

When the wipers encounter their respective bank contacts 64, 58 and 59, the call finder CF is automatically stopped. This is brought about by the wiper 61 encountering bank contact 64, which, it will be recalled, had ground placed on it from grounded armature 4l of relay 40, which ground is now extended from wiper 61, to armature 81 and its front contact on relay 85, to the upper windings of relays 80 and 15 to battery. Relay 15 immediately operates its armature 15 to open the circuit of stepping magnet 9i) and prevent further rotation of the wipers. At back contact and armature 8l relay 88 opens a further point in the circuit of stepping magnet 90. At armature 82 and its back contact the start circuit 63 for energizing relay 85 is opened and this relay slowly restores its armatures. Its armature 81 remaining, however, closed for a short time after the deenergization of the relay in order to insure complete operation of relays 15 and 80. Relay 88 at its front contact on armature 83 closes a locking circuit for itself extending to wiper 61 and its grounded bank contact 64, upon which it is now resting. -Relay 15 deenergizes after relay 85 has completely deenergized;

At the time that relay 40 energized the start conductor 53 was grounded by armature 42. A branch of this grounded circuit extends by way of back contact and armature 5l through the call lamp CL to battery. The illumination of this call lamp CL informs the drivers at the cab-stand of the presence of a call from some call station, although the exact location is not known. If desired this lamp may be arranged to be dashed similar to the manner in which the lamp FL of Fig. 2 is operated. In response to the dashing of the lamp CL at the cab-stand a driver will insert a special key into a lock 18 so as to close contact springs 19. This action precludes the possibility o unauthorized personsV using the service. The handset HSZ is then removed from the switchhook by the driver thereby resulting in the closing of contacts 14 to extend ground through these contacts, contacts 19, through the winding of relay 58 to battery. Relay 58 upon energizing closes its front contacts on armatures 5l and 52. At front contact of armature 53 ground is extended through the winding of slow to release relay 55 to battery. At armature 54 and its back contact a point in the releasing circuit which will later be pointed out in more detail, is opened.

vAs a result of the energization of slow release relay 55 armature 56 is opened from its back contact to open a point in the start conductor 63 in order to prevent further operation of the call nder switch CF, should additional calls be made at this time. At armature 51 and its front contact a point in the release circuit is closed.

As a result of the closing of front contacts of armatures 5| and 52 of relay 59 a loopcircuit is closed extending through the handset I-ISZ, the aforesaid contacts and armatures, line conductors 88 and 89 extending to the supervisors position, normally closed contacts of ringing key RK, normally closed contacts of display key DK, through the windings of relay 11 to ground and battery, respectively. Relay 11 energizes, and at its grounded front contact and armature 84 completes a circuit to the supervsors call lamp SL. The operator at the supervisors position noting the illumination of the lamp L, thereupon operates the talking key TK to close the normally open contact springs and also removes the handset HSI from the switchhook to engage in conversation with the driver at the cab-station, talking battery for each handset being furnished through the windings of relay 11. The driver at the cab-stand informs the supervisor of the existence of a call for a cab by a patron and also informs the supervisor of his particular cab or his number. The supervisor notes this information and thereupon actuates the display key DK. This opens the normally closed contacts including the talking circuit through this key and closes the normally open contacts, thereby extending grounded generator from the alternating current generator through both normally open contacts of the display key DK over both conductors 88 and 89, armatures 5| and 52, and their front contacts, through both windings of impedance coil 13 to a common junction point, and then through the windings of alternating current relay 65 and the condenser C to ground. The alternating current flowing through this circuit energizes relay 65 which upon operating closes its grounded front contact on armature 56 through to the winding of relay 18 to battery. Relay 10 is thereby energized and locks up through its front contact and armature 1I to the conductor extending to wiper 61 which is resting on grounded bank contact 64. With relay 10 locked up the supervisor may restore the display key DK. As a further result of the energization of relay 18 ground is placed on the front contact of armature 12 through wiper 69, bank contact 59, through lamp L-I to battery. The illumination of lamp L-I at the cab-stand informs the driver thereat of the particular line and therefore the location from which the call has been made, which in this instance, has been assumed to be call station A. The driver will transmit this information verbally over line conductors 88 and 89 to the supervisor, whereupon the supervisor Will restore the talking key TK and replace the handset HSI upon the switchhook.

The driver at the cab-stand noting the location of the call will replace his handset HSZ upon the switchhook thereby opening contacts 14. He will likewise remove the key from the lock 18 opening contacts 19. As a result, relay 5D has its energizing circuit opened, and it restores its armatures 5I and 52, thereby opening the line circuit 88 and 89 to the supervisors position, while at front contact of armature 53 the circuit of relay 55 is opened, and this relay slowly deenergizes. At the back contact of armature 54, when relay 50 has completely deenergized, battery is extended through low resistance 44, back contact of armature 54, and before front contacts of armature 51 have been completely opened, this circuit extends to wiper 68 and bank contact 58 upon which it is now resting over conductor 92 to line conductor 2 to the call station A through contact springs I and 9 and the winding of release magnet 5 to ground. The resistance 44 shunts out relay 40 and is low enough for release magnet 5 to energize in series with it. The magnet 5 thereupon operates the locking latch of its armature 1 to permit the restoration of push button 8 and the contacts I0 and I I to assume their normal position. Shortly after release magnet 5 has completely energized slow releasing relay 55 has completely restored its armature 51 thereby opening the above traced energizing circuit for releasing magnet 5. With the push button 8 restored to its normal position the release magnet 5 is again included in the line circuit 2 over its front contact and armature 9 through the winding of high resistance 49 to battery. But as this release magnet is wound so that it does not energize or remain held up in series with the relatively high resistance of relay 49 it immediately falls back and at armature 5 opens the circuit of relay 40 which thereupon restores its armatures 4I and 42. At armature 9| and its front contact ground is removed from the bank contact 84 upon which Wiper 61 is resting to open the locking circuit of relay at armature 83 and. of relay 19 at its armature 1I. Relay 10 upon restoring its front contact from its armature 12 extinguishes the lamp L-I over the circuit extending from wiper 69 and bank contact 59. Relay 89, upon restoring its armature 82 to its back contact again closes the start circuit 63 to relay 85. Start circuit 53 has in the meantime been opened by ground being removed from armature 42 by relay 48. Call lamp CL is also extinguished by armature 42 opening. The restoration of the push button 8 at the call station A informs the waiting patron that his wishes for cab service have been complied with and that a cab has been dispatched to the immediate location of the call station A. The call finder switch CF remains in the position last used with its Wipers resting on the bank contacts with which it is in engagement.

Should the operator at the supervisors position desire to communicate with any of the drivers at the cab-stand he may do so by operating the ringing key RK onto its normally open contacts to close the alternating current generator current through the primary and secondary windings of the transformer TR to line conductors 88 and 89 and through condenser Cl and the windings of alternating current relay 69. Relay 60 upon energizing closes its grounded front contact on armature 62 to battery through the loud ringing bell B. At its grounded contact and armature 8| it closes the circuit through call lamp CL to battery. By properly manipulating the ringing key RK in any desired manner the call lamp CL and the bell B may be caused to flash and sound periodically. The driver at the cab-stand responds to these signals by unlocking the'lock 18 and removing the handset HSZ to close contacts 14 and 19 and operate relay 59. Relay 50, upon operating, closes its front contacts on its armatures 5I and 52 so that when the ringing key RK is restored between ringing intervals relay 11 is energized to close its arma- .control station, and means at said control station ture 84 on' its grounded front contact to illuminate the lamp SC and advise the supervisor that his call is answered, whereupon he may operate the talking key TK and engage the driver in conversation over handset HSI. At armature 53 and its front contact relay 5B closes a circuit to relay 55 which at its armature 5S in turn opens a point in the start circuit 63 to prevent the reception of incoming calls at this time. The release of the equipment is in a manner similar to that previously pointed out.

From the foregoing description of the operations performed during the existence of a single call, it will be appreciated that a relay such as 40 will be provided for each individual line and that each line may have any number of call stations, A, B, C, etc., connected in series with it. 'Ihe call nder CF in its operation seeks the particular line on which a call has originated and indicates the particular line to the cabdriver. This indication is effective only through the act of the cab driver in calling the supervisors position so that a permanent record and adequate supervision is maintained of all calls for taxi-cab service. This greatly facilitates the movement of the vehicles and renders it unnecessary for them to continuously cruise about the city for passengers. It likewise concentrates the idle taxi-cabs at a common central location Where they are rendered immediately available to any patron desiring their services. The patron is at all times informed of the response to his request for service by noting the action of his call button 8 in releasing at the call station.

It will be appreciated that metering of calls may be performed in the same manner as shown in Fig. 2. A line call meter can be connected to contacts of relay QB, while a meter to register total calls from a cab stand may be connected to contacts of relay Il.

It may occasionally be desirable for the cab driver to report his arrival at any cab-stand to the supervisors position. He may do so by operating a push button at the cab-stand arranged in a manner similar to that of call station A, whereupon he may by means of his handset HS2, and in a manner previously pointed out, engage in conversation with the supervisor.

The invention is not limited in its application to a vehicle control system as described but may be used in connection with watchmans service, re alarm, and other similar signaling systems.

Having described the invention what is considered to be new and is desired to be protected by Letters Patent will be set forth in the following claims:

What is claimed is:

1. In a signaling system, a control station, a line, calling stations connected in series to said line, a key at each of said stations together with means for locking it in operated position, means for signaling said control station over said line from each of said stations responsive to the operation of the associated keys, and means at said control station for controlling said locking means over said line to unlock said keys in succession.

2. In a signaling system, a plurality of calling stations, a calling key and a magnet at each of said stations for restoring said key from an operated position, 'a control station connected over a line circuit with said calling stations, a signal relay at said control station, the operation of any number of said calling keys operating said signal relay over said line circuit to signal said for releasing said signal relay and at the same time operating said magnets back over said line circuit to release saidcalling keys in successive order.-

3. In a signaling system, a plurality of calling stations, a calling key at each station mechanically locked when operated, a magnet at each station for restoring said key from operated position, a control station, a signal relay and a release key at said control station, a line circuit connecting said stations in serial relationship, the operation of said calling keys repeatedly operating said signal relay over said line circuit, a signal operated by said signal relay, the operation of said release key successively operating said magnets over said line circuit to restore said calling keys one after another to normal.

4. In a signaling system, a control station, lines extending from said control station, a plurality of call stations connected in serial relationship on each of said lines, a calling key together with means for locking said key in operated position at each of said calling stations, a release magnet for controlling said locking means, a release key and a signal relay at said control station for each line, the operation of any of said calling keys on a line operating the associated signal relay over the line to signal the control station, the

operation of other calling keys on the same line u rendered ineffective to control said signal relay until said iirst calling key is restored, said release key operated to operate said release magnet to control said locking means over said line to release said operated calling key, and means controlled by each releasemagnet in turn as it is operated by said release key to connect up succeeding call stations on the same line.

5. In a signaling system, a control station, a line extending from said control station, a plurality of call stations connected in serial relationship on said line, a calling key and means for locking said key in operated position at each calling station, a release magnet for controlling said locking means, a release key and a signal relay at said control station, the operation of one of said calling keys operating said signal relay over the line to signal said control station and to disconnect the other stations from the line while permitting their associated calling keys to be locked in operated position, said release key o-perated to operate said release magnet to control said locking means to release said rst operated calling key and upon restoration of said key and said release magnet connect the next calling station to said line to operate said signal relay again from the next operated calling key.

6. In a signaling system, a control station, a line extending to said control station, a plurality of call stations connected in serial relationship to said line, a calling key at each of said stations, signaling means at said control station, means responsive to the operation of one of said calling keys for operating said signaling means o-ver said line and for locking said key in operated position, the operation of all or any of the other of said calling keys at the same time eiTective only to lock them in operated position, and means at said control station for controlling said locking means over said line at each of said stations to unlock the keys one at a time and permit the key of the next station to operate the control Station signaling means.

'7. In a signaling system, a control station, a calling station having a calling key, a line connecting said stations, signaling means at said control station, the operation of said calling key operating said signaling means over said line, a supervisors position, a telephone line connecting said supervisors position with said control station, a registration means at said supervisors position, said registration means operated over said telephone line responsive to the operation of said signaling means at said control station, means for establishing a telephone connection between said control station and said supervisors position, and means at said supervisors position for determining Whether the telephone line is to be used for a telephone connection or for operating the registration means.

8. In a signaling system, a control station, a calling station having a calling key, a line connecting said stations, signaling means at said control station, the operation of said calling key operating said signaling means over said line, a supervisors position, a telephone line connecting said supervisors position with said control station, a registration means at said supervisors position, said registration means operated over said telephone line responsive to the operation of said signaling means at said control station, means for establishing a telephone connection between said control station and said supervisors position, and a differential relay at said super- Visors position variably operated depending o-n whether the telephone line is used for a telephone connection or for operating the registration means.

9. In a signaling system, a control station, a calling station connected to said control station, means at said calling station for signaling said control station, a supervisors position connected to said control station, registration means at said supervisors position, means for operating said registration means responsive to the signaling of said control office by said calling station, means for establishing a telephonie connection between said control station and said supervisors position, and means in said supervisors position for differentiating between a registration or a telephone call.

10. In a signaling system, a control station, a calling station connected to said control station, means at said calling station for signaling said control station, a supervisors position connected to said control station, a registration means and a calling signal at said supervisors position, a differential relay for controlling said registration means and said calling signal, means for operating said diierential relay in one manner to actuate said registration means responsive to the signaling of said control station by said calling station, and for operating said differential relay in another manner to actuate said calling signal responsive to the establishment of a telephone connection between said control station and said supervisors position.

l1. In a signaling system, a control station, a plurality of lines extending from said control station, calling stations on each of said lines, a selective switch at said control station, means at said calling stations for signaling said control station over the line on which the calling station is connected, means responsive to said signal for operating said selective switch to nd the calling line, and means controlled at said control station for indicating at said calling station that said signal has been received.

12. In a signaling system, a control station, a plurality of lines extending from said control station, calling stations on each of said lines, a selective switch at said control station, means at 10 said callingV stations for signaling said control station over the associated calling line, means responsive to said signal for operating said selective switch to find the calling line, a supervisors position connected to said control station over a telephone line, means responsive to the establishment of a telephone connection over said telephone line for giving an indication at said control station of the signaling line from which the calling station signaled, and means responsive to the disconnection of said telephone connection for releasing said switch and for giving an indication at said calling station that the signal is received.

13. In a signaling system, a control station having a plurality of lines connected to it with each line containing a plurality of call stations,

a selective switch having line indicating means, means at a call station for signaling the control station over its line and for operating said selective switch to nd the line, a supervisors position connected to said control station over a telephone line, means at said control station for signaling said supervisors position to establish a telephone connection over said telephone line,

means at said supervisors position for actuating the line indicating means in said selective switch over said telephone line, and means responsive to the disconnection of said telephone connection for releasing said selective switch and for giving an indication at said calling station that the call has been answered.

14. In a signaling system, a control station having a plurality of lines connected to it and each line having a plurality of call stations arranged on it, a selective switch having line indicating means, locking means at a call station for signaling the control station over its line and for operating said selective switch into engagement with the calling line, a supervisors position connected to said control station over a telephone line, means at said control station for signaling said supervisors position over said telephone line to establish a telephone connection, means at said supervisors position for transmitting grounded generator current over both sides of said telephone connection to operate the line indicating means in said selective switch, means responsive to the disconnection of said telephone connection for releasing said selective switch and for unlocking the calling means at the calling station, and means at said supervisors position for transmitting generator current over a loop circuit over said telephone line to signal said control station.

HARVEY L. HARRIS. BERNARD D. WILLIS. 

